LTE (Long Term Evolution) is the evolution of 3G (3rd Generation) and improves and enhances air access technology of 3G, and OFDM (Orthogonal Frequency Division Multiplexing) and MIMO (Multiple Input Multiple Output) are adopted as standard for wireless network evolution of this LTE. Therein, in LTE system and the previous wireless communication system, there is one carrier in a cell. As shown in FIG. 1, the maximum bandwidth in LTE system is 20 MHz. And under spectral bandwidth of 20 MHz, LTE can provide peak rate of 100 Mbit/s at downlink and 50 Mbit/s at uplink to improve the performance of cell edge user, increase cell capacity and decrease system delay. Besides, in LTE system, UE (User Equipment) can work under only one carrier, and there is only one carrier in a cell, so each LTE cell is identified by a unique number in the network.
Along with the rapid increase in the quantity of mobile terminal users, the service capacity of terminal users increases exponentially. To meet the service demand of the increasing terminal users, it is necessary to provide a greater bandwidth to realize higher peak rate required for terminal users' service and application. In LTE-A (LTE Advanced) system, the peak rate is greatly improved compared with LTE, which is required to be 1 Gbps at downlink and 500 Mbps at uplink. In this case, only using the carrier with maximum bandwidth of 20 MHz can hardly achieve the requirements of peak rate. Therefore, LTE-A system needs to expand the bandwidth available to terminal user, thus the introduction of CA (Carrier Aggregation) technology, that is, aggregate several continuous or discontinuous carriers under the same eNB (evolved Node-B,) (aggregation is unavailable between cells or component carriers under different eNBs) and serve UE, so as to provide the required rate. These aggregated carriers are also called CC (Component Carrier). In addition, to ensure UE of LTE can be work under each aggregated carrier, each carrier for aggregation cannot exceed 20 MHz at most. FIG. 2 shows CA technology of LTE-A, where there are 4 carriers that can be aggregated under the eNB of LTE-A, and the eNB can perform data transmission on 4 carriers and UE simultaneously, to improve system throughput.
In course of implementing the present invention, the inventor finds out there are at least the problems below in the present technology:
In present technology, UE only works in the separate cell and only informs the network of band supported by it, instead of its carrier aggregation capability, thus the base station cannot configure carrier aggregation for UE in the carrier aggregation context.